微型离心叶轮流动损失分析与削弱

Analysis and Reduction of Flow Loss in a Micro Centrifugal Impeller

关键词:  离心压气机  流动机理  损失削弱  数值模拟  微型发动机 

Key words:  Centrifugal compressor  Flow mechanism  Weakening loss  Numerical simulation  Micro turbine engine

摘要:

为了研究削弱微型离心叶轮内损失、提高其性能的方法,采用S-A湍流模型对微型涡喷发动机离心叶轮流动进行了三维数值模拟 。分析表明流场中存在的三个主要涡流区是显著的损失源,它们的形成机理与通道内展向静压分布不均匀性造成的压力梯度有关。因此,从改善展向压力分布的角度对叶轮进行了改进设计以削弱流动损失。结果表明通过改进叶轮轴向长度、分流叶片前缘的位置和形式以及主叶片的叶片角分布可改善子午流道、分流叶片吸力面和通道内S2流面等处的展向静压分布,使之变化减缓、梯度降低,从而削弱了涡流的损失,使堵塞流量增加了约15%,叶轮峰值效率提高约7%,压比提高约6%。 

Abstract:

In order to investigate the way of weakening the flow loss and improving the performance of the micro centrifugal impeller, an impeller used in a micro turbine engine was analyzed by three-dimensional numerical simulation with S-A turbulence model. The analysis shows that three dominant eddies in the flow field are the significant loss source, and their generation mechanism relates to the nonuniform distribution of the spanwise static pressure in the impeller passage. Consequently, the impeller was redesigned by improving the spanwise static pressure distribution uniformity to weaken the flow loss. It showes that the spanwise static pressure distribution uniformity on the meridian plane, the splitter suction surface and the S2stream surface can be smoothed by improving the axial length of the impeller, the position and form of the splitter blade leading edge, and the main blade angle. Their gradient is reduced, and then eddy loss is weakened.As the results,the choking flow rate increases by about 15%, the impeller peak efficiency increases by about 7%, and the pressure ratio increase by about 6%. 